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624, 1249, 1874, 2499, 3124, 3749, 4374, 4999, 5624, 6249, 6874, 7499, 8124, 8749, 9374, 9999, 10624, 11249, 11874, 12499, 13124, 13749, 14374, 14999, 15624, 16249, 16874, 17499, 18124, 18749, 19374, 19999, 20624, 21249, 21874, 22499, 23124
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OFFSET
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1,1
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COMMENTS
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The identity (625*n-1)^2-(625*n^2-2*n)*(25)^2=1 can be written as a(n)^2-A158373(n)*(25)^2=1.
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LINKS
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FORMULA
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a(n) = 2*a(n-1)-a(n-2).
G.f.: x*(624+x)/(1-x)^2.
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MATHEMATICA
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LinearRecurrence[{2, -1}, {624, 1249}, 50]
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PROG
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(Magma) I:=[624, 1249]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];
(PARI) a(n) = 625*n - 1.
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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